The best and worst…. residual values

Do you know how well – or badly – the new car you're considering will depreciate over three years? Find out more here.

Depreciation is the single biggest cost of car ownership, so buying a new car without understanding this key part of the equation could cost you dear.

Whatcar.com has resale values for every new car on sale, so use our depreciation tool to arm yourself with the facts before you buy.

We've crunched the numbers to find out which car has the best overall resale percentage – and which has the worst.

The more you spend on a new car the more you stand to lose, too, so we've also been to the top and the bottom of the table to search out the cars that shed the most and least cash.

Strongest resale percentageThe Audi TT has the most solid three-year resale value of any car currently on sale – at 71% for a 2.0 TDi 170 Quattro.

That means the £27,375 car will have lost £7880 after three years and 36,000 miles and be worth around £19,495.

The rest of the diesel coupe range hits 70%, while the convertibles retain up to 69% of their value.

Weakest resale percentageCitroen's Xsara Picasso is at the bottom of the heap, holding on to jut 20% of its original value over three years.

From the list price of £17,695 for the 1.6i 16V 110 Desire, you'll be left with just £3599 after three years – a plummet in value of £14,096.

Part of the reason the Picasso's resale value is so poor, however, is down to the massive discounts you can get when you buy it.

By checking the What Car? Target Price you can see that you shouldn't pay more than £11,945, which slashes the losses to a slightly less eye-watering £8346.

Least cash lostIf you want to lose the least cash over three years, you need to start with a low list price in the first place.

Thanks to a low list price of £6635, and a good resale percentage of 43%, the Kia Picanto comes out on top by losing just £3755 over three years and 36,000 miles.

The Volkswagen Fox runs the Kia close with £3810 lost over three years on the £7460 1.2 54bhp car.

Most lostGo to the other end of the spectrum with the £153,341 long wheelbase Mercedes-Benz S65 AMG luxury performance car and the story is very different.

It retains just 32% of that original pricetag over three years – so pay in full up front and you're looking at a whopping £103,715 loss over three years. That's just short of £95 depreciation for every day of ownership.